Of course, it has always had its limitations. Most obviously, it is one dimensional, making no allowance for the fact that the positions that people and parties hold on different policies don’t always align in a uniform way. For instance, one member of a political party may be middle-of-the-road on economic policy, a dyed-in-the-wool conservative on social issues and a resolute anti-interventionist in foreign affairs; meanwhile, another member of the same party could be a gung-ho free marketeer, a dripping-wet liberal in the social sphere and an enthusiast for military intervention on the world stage.

Clearly, the left-right spectrum can’t represent these multi-dimensional permutations. Then again, it doesn’t have to. Given that elections are about basic choices, mostly economic, a single dimension gets the job done.

However, what works for clarifying electoral politics doesn’t always work for classifying political ideology. For instance, where do we put the various kinds of populism currently disrupting conventional politics – especially those described as rightwing populism? Do we place them to the right of the mainstream conservative parties, as is physically the case in the European Parliament? The problem with that is that populist economic policies are usually to the left of what conservatives advocate and sometimes far to the left.

And where does libertarianism go? Should we tack that onto the right end of the spectrum too? Not if it means lumping it in with authoritarian ideologies to which it is diametrically opposed.

To try to resolve these contradictions, various attempts have been made to change the way that we classify politics.

Sorry libertarians, but it’s not all about you

One approach is to add a second axis to the conventional left-right spectrum – the two axes intersecting at right angles to create a two-dimensional continuum. Examples include the Nolan Chart and the Political Compass.

Typically, one axis is about how much or how little government should intervene in economic matters, while the other is about how much or how little regulation there should be of non-economic matters. Essentially, both axes are about (personal) liberty versus (collective) authority and therefore, unlike the conventional political spectrum, they do a good job of clearly separating libertarians from conservatives, the liberal left and various kinds of authoritarian.

However, this way of thinking about political differences does rather revolve around libertarian assumptions. The value of freedom is elevated above all others – and, furthermore, defined in direct opposition to the role of the state. The idea that government, or other sources of authority, might be an enabler of freedom is designed out from the start.

But perhaps the strongest argument against concepts such as the Nolan Chart is that real-life politics refuses to organise itself in any such fashion. Though libertarian parties exist in many western countries, very few have had a significant impact on mainstream politics. Indeed most are on the fringes, not even qualifying for minor party status.

The populist surge currently disrupting conventional left-right politics is not a libertarian revolt. Admittedly, it is not a demand for less freedom either; but that only underlines the fact that the current realignment of politics is about something else completely.

Sorry centrists, but it’s not all about you either (whoever you are)

A different solution to the limitations of left-right spectrum is to stick to a single dimension, but to stop visualising it as a straight line. A straight line maximises the distance between extreme left and extreme right, but if you bend it into a horseshoe shape, then the extremes curve back round towards one another. Shaped in this way the greatest distance between any two points on the line is between the centre and either extreme.

The horseshoe model of politics has a lot going for it – not least in reflecting the commonalities between extreme left and extreme right. It seems especially applicable to French politics where a centrist candidate (Emmanuel Macron) defeated opponents on the hard left (Jean-Luc Melenchon) and the hard right (Marine Le Pen) to win the Presidency. It also help us visualise how a great deal of the National Front’s voter base defected directly from the left,1 without going on a political ‘journey’ via the centre.

However, like a real horseshoe, this model of politics is full of holes. It strongly implies the existence of a second and more important political axis running between centrism and extremism, but doesn’t say what it is. Who are the centrists, anyway? Metropolitan liberals? Localist communitarians? Technocratic pragmatists?

The only firm definition of political centrism is that it lies between the extremes – and yet the whole purpose of the horseshoe is to bring those extremes closer together. As a model of political opinion it is incoherent and paradoxical.

We can’t even identify centrism with the strongest support for democracy. The weakening of such is a worrying long-term trend identified by Yascha Mounk and others.2 One might logically associate it with the growing polarisation of politics. And yet recent research suggests that the loss of faith in our democratic institutions has gone further among self-identified centrists than among those on the Left or the Right. The same research found that “support for a strong leader who ignores his legislature” is also strongest among self-declared centrists.3

The most plausible explanation for these perplexing results is that it isn’t just political moderates who claim the centre as their home, but also their temperamental opposites – people who are fed-up with the political establishment and everything about it – including conventional categories of Left and Right.

Leaving aside the special example of France, it seems clear that centrism is no more useful a reference point for the new politics than libertarianism is.

There is, however, a much much stronger candidate for a new political spectrum.

How open-and-closed got its start

Ruth Davidson is the young and charismatic leader of the Scottish Conservative Party. She is a confidante of the Prime Minister Theresa May and widely tipped as a future, if not immediate, successor. Interviewed in Vogue earlier this year, she was asked whether she worried about the “Tory brand becoming re-toxified.” Her answer was full of significance:4

“My worry is actually much greater than that… My worry is that we’re about to head into a culture war around the world where it’s not a question of left versus right any more – it’s a question of open versus closed. We’ve spent a long time believing there was a consensus about the idea of freedom and interaction and breaking down borders, and then suddenly they’re all being built back up again. That’s what I think the fight is going to be about, and I’m damn sure going to take part in it.”

Where does the concept of open-versus-closed come from and what exactly does it mean?

One of the earliest and best references comes from the opinion pollster Stephan Shakespeare. This is what he said in the Guardian at the time of the 2005 UK general election:5

“…there is a new line which separates one side of the electorate from another: recent YouGov research suggests that we no longer range along a left-right axis, but are divided by ‘drawbridge issues’.

“We are either ‘drawbridge up’ or ‘drawbridge down’. Are you someone who feels your life is being encroached upon by criminals, gypsies, spongers, asylum seekers, Brussels bureaucrats? Do you think the bad things will all go away if we lock the doors? Or do you think it’s a big beautiful world out there, full of good people, if only we could all open our arms and embrace each other? Depending on which side we take, we regard ‘drawbridge up’ people as unpleasant, or ‘drawbridge down’ people as foolish.”

He didn’t actually use the terms ‘open’ and ‘closed’ – but they’re clearly equivalent to “drawbridge down” and “drawbridge up.”

A year later, Tony Blair, then British Prime minister, gave a speech to the TUC annual conference, in which open versus closed made its political debut:6

“There is a debate going on which, confusingly for the politicians, often crosses traditional left/right lines and the debate is: open v closed.

“Do we embrace the challenge of more open societies or build defences against it?”

The year after that, following his resignation as Prime Minister, Blair devoted a whole speech to this concept:7

“the real dividing line to think of in modern politics has less to do with traditional positions of right versus left [and] more to do today with what I would call the modern choice, which is open versus closed.”

Though thoroughly biased towards the open point-of-view, the speech had its prescient moments:

“….you’ll find the open and the closed on either of the traditional political categories of right and left. And it has got some fascinating implications, actually, for electoral calculations.”

Of course, by the time the speech, Blair was out-of-office and out-of-favour with fashionable opinion. His thoughts on open-versus-closed were largely ignored over most of the following decade.

In that time, there were many indications that populism was growing in strength.For instance, the arrival of Five Star as a major party in the 2013 Italian general election and the results of the 2014 European Parliamentary elections. However, these could be dismissed a protest vote against the financial crisis and its aftermath.

One of the few commentators to realise that something more important was going on on was an UnHerd contributor, James Kirkup. Writing for the Daily Telegraph in 2014, he argued that left-and-right were of diminishing relevance – especially in describing the distinctions between the parties of the political establishment and their populist challengers:8

“…the terms ‘Right’ and ‘Left’ are becoming meaningless.

“After all, if those labels were useful, they’d tell us how people who carry them would think about particular subjects. Left-wingers, for instance, would be hostile to free markets and big business, while Right-wingers would embrace them. It’s a nice, clean theory, but the reality is much messier.”

Referring to a proposed free trade agreement between The US and EU, he said that open-versus-closed would be a better to guide to the politics of the future:

“So keep watching TTIP. Dry and dusty it may be, but the way our politicians deal with it will tell you much more about them than any label putting them on some meaningless left-right spectrum.

“Forget Left and Right. The real political division of the 21st Century is the same as it was in the 19th. Should we be open or closed?”

He didn’t have to wait long to be vindicated. 2016 was the year that the vote for Brexit redefined British politics and the election of Donald Trump redefined American politics. In 2017, Marine le Pen reached the final round of the French Presidential election, gaining a third of the vote.

Anti-populists took heart from the fact that her centrist opponent got twice as many votes. They were also encouraged by a disappointing result for Geert Wilders’s PVV in the Dutch general election (his party having lost a clear opinion poll lead to come in a poor second).

However, hopes that the surging populist tide of 2016 had been turned back in 2017 were soon to be dashed. In last year’s German general election, the AfD doubled its vote to become the biggest opposition party in the Bundestag – forcing a weakened CDU and SPD into yet another reluctant coalition. Meanwhile, Angela Merkel’s Austrian counterpart, Sebastian Kurz, won the legislative election by taking his party to the right on immigration. He then turned right again – selecting the Freedom Party as his coalition partner. Over the border, Victor Orban won a crushing victory (the third in a row) in this year’s Hungarian general election.

In any case, the fact that ‘open’ sometimes wins doesn’t alter the reality that open-versus-closed is displacing left-versus-right as the most important political divide.

This year’s Italian general election was an especially symbolic moment. Italy has a large number of parties, but traditionally they organise themselves into two main blocs – one on the centre-right and one on the centre-left. The names of the two blocs and their precise membership changes from election to election, but each time it amounts to much the same thing. Or, at least, it did.

The first blow to the old order came from the emergence of the populist Five Star Movement as powerful force unaligned to either bloc. The second blow has come from the rise of the League – a populist party of the hard right. The League fought the 2018 election as part of the centre-right and was expected to follow the lead of what had been the biggest party in the bloc: Silvio Berlusconi’s Forza Italia. Except that, as UnHerd’s Henry Olsen predicted,9 things turned out differently. Five Star won the election, but the League came second – and well ahead of Forza Italia. In the subsequent negotiations to form a government, the League dumped its centre-right partners to form a coalition with the other big populist party – Five Star.

Not for the first time, the organising logic of open-versus-closed is proving to be more powerful than that of left-versus-right.

After Brexit, after Trump, after Italy, there is no more ignoring the new reality. Left-and-right is not dead yet, but open-and-closed is nevertheless redefining politics. Therefore there’s a lot riding on what is actually meant by open and closed.